Rollover Protection Apparatus

ABSTRACT

A rollover protection apparatus unlocks and lowers from a raised position to a lowered position suitable for clearing a low hanging obstacle when an operator applies a force to an operator lever or pedal. The rollover protection apparatus returns to the raised position when the operator ceases applying force to the operator lever or pedal.

RELATED APPLICATIONS

This application is a continuation of co-pending application Ser. No.14/540,708 filed on Nov. 11, 2014, which is incorporated herein byreference. U.S. patent application Ser. No. 14/540,708 was acontinuation of U.S. patent application Ser. No. 13/655,014 filed onOct. 18, 2012, which is now U.S. Pat. No. 8,905,434 and which isincorporated herein by reference. U.S. patent application Ser. No.13/655,014 was a Continuation-in-Part of U.S. patent application Ser.No. 12/945,277 filed on Nov. 12, 2010, which is now U.S. Pat. No.8,528,924 and which is incorporated herein by reference. U.S. patentapplication Ser. No. 12/945,277 claimed the benefit of U.S. ProvisionalPatent Application Ser. No. 61/281,059 filed on Nov. 12, 2009 which isincorporated herein by reference.

FIELD

This invention relates to a rollover protection apparatus which movesfrom a raised position to a lowered position suitable for clearing a lowhanging obstacle.

BACKGROUND

Numerous rollover protection apparatuses may be found in the prior art.Various prior art rollover protection apparatuses teach various ways forfolding down, retracting or telescoping a upper portion of a roll barassembly usually in order to clear low hanging obstacles. Typically, theprior art teaches various types of joints that can be manually adjustedto lower the upper portion of a roll bar assembly. A problem that ariseswhen using prior art retractable rollover protection apparatuses ariseswhen an operator begins work in an area which includes low hangingobstacles. The potential exists for an operator to merely place theupper portion of a roll bar assembly in a lowered position prior toworking in such an area. If the same area also includes a sloped surfaceand the operator fails to return the upper portion of the roll barassembly to the raised position suitable for protecting the operatorduring a roll over, the operator will be exposed to a roll over hazard.What is needed is a rollover protection apparatus wherein an operatormay quickly and temporarily lower the upper portion of a roll barassembly to clear a low hanging obstacle and which automatically returnsto a raised position when the operator is no longer acting to cause theupper portion to be lowered. With such a rollover protection apparatus,the upper portion of the roll bar assembly would lower only as needed toclear low hanging obstacles and would otherwise remain in a raisedposition suitable for protecting the operator during a roll over.

SUMMARY

In order to overcome the above stated problems and limitations there isprovided an improved rollover protection apparatus for a vehicle whichmay be selectively lowered to clear low hanging obstacles. The improvedrollover protection apparatus includes a roll bar assembly and alowering and raising mechanism. The roll bar assembly includes a lowerportion that is mounted to the vehicle frame and an upper portion thatis mounted to the lower portion. The upper portion is movably mounted tothe lower portion so that the upper portion may move between a raisedposition and a lowered position. A lock is associated with the upperportion and the lower portion such that when the upper portion is in theraised position, the lock secures the upper portion sufficiently to thelower portion so that the roll bar assembly will support the vehicle andprotect the operator should the vehicle rollover.

The raising and lowering mechanism includes an operator lever. Theoperator lever may take the form of a handle, a foot pedal or any othermovable element suitable for receiving a manually applied force from anoperator. The raising and lowering mechanism is adapted so that when theoperator of the vehicle applies sufficient force to the operator lever,the raising and lowering mechanism unlocks the upper portion of the rollbar assembly and urges the upper portion to move from the raisedposition to the lowered position. The raising and lowering mechanism isalso adapted so that when the operator ceases applying force to theoperator lever, the upper portion moves from the lowered position to theraised position at which point the lock re-engages.

Accordingly, an operator using the improved rollover protectionapparatus may apply force to the operator lever to cause the upperportion of the roll bar assembly to move to the lowered position toclear an low hanging obstacle. When the vehicle has cleared the lowhanging obstacle, the operator can stop applying force to the operatorlever thereby allowing the upper portion of the roll bar assembly toreturn to the raised position where the lock re-engages to sufficientlysecure the upper portion in the raised position to protect the operatorshould the vehicle roll over.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the improved rollover protectionapparatus installed on a vehicle.

FIG. 2 is a side view showing an operator lever mounted to the vehicle.

FIG. 3 is a perspective view of a roll bar assembly.

FIG. 4 is a close up perspective view of one side of the roll barassembly shown in FIG. 3.

FIG. 5 is a close up side view of the roll bar assembly showing theupper portion in the upright position with the lock engaged.

FIG. 6 is a close up side view of the roll bar assembly showing upperportion in the upright position and with the lock disengaged.

FIG. 7 is a close up side view of the roll bar assembly showing theupper portion in a position which is between the raised position and thelowered position and showing the lock disengaged.

FIG. 8 is a close up side view of the roll bar assembly showing theupper portion in the lowered position and the lock disengaged.

FIG. 9 is a perspective view of a second embodiment of a rolloverprotection apparatus showing the upper portion of the roll bar assemblyin a raised position.

FIG. 10 is a rear view of the second embodiment of the rolloverprotection apparatus showing the upper portion of the roll bar assemblyin the raised position with locking mechanism engaged.

FIG. 11 is a rear view of the second embodiment of the rolloverprotection apparatus showing the upper portion of the roll bar assemblyin the raised position with locking mechanism disengaged.

FIG. 12 is a rear view of the second embodiment of the rolloverprotection apparatus showing the upper portion of the roll bar assemblyin the lowered position and the upper portion actuator cable fullyextended.

FIG. 13 is a perspective view of the second embodiment of the rolloverprotection apparatus showing the upper portion of the roll bar assemblyin the lowered position.

FIG. 13A is a magnified perspective view of the second embodiment of therollover protection apparatus showing the details of the pivot jointbetween the lower portion and the upper portion of the roll barassembly.

DETAILED DESCRIPTION

Referring to the drawings, FIG. 1 shows an example embodiment of theimproved rollover protection apparatus 10 installed on vehicle 5. Inthis example, vehicle 5 may be any type of vehicle but will mosttypically be a riding lawn mower, tractor or other such vehicle which islikely to be exposed to a risk of a roll over. As can be seen in FIG. 1,improved rollover protection apparatus 10 includes a roll bar assembly12, a raising and lowering mechanism 50 and an operator lever assembly50. Roll bar assembly includes a lower portion 14 which is fixed to theframe of vehicle 5 and a upper portion 30 which is pivotably mounted tolower portion 14.

As can be best seen by referring to FIG. 3, lower portion 14 of roll barassembly 12, in this example, includes two spaced bottom members 16A and16B. Each of the two spaced bottom members 16A and 16B have upper ends18A and 18B respectively and lower ends 19A and 19B respectively where,in this example, may be found bolt holes 19H for receiving bolts (shownin FIG. 1) for fixing bottom members 16A and 16B to the frame of vehicle5. As can be seen in FIG. 3, upper portion 30 includes two side members32A and 32B. Each side member 32A and 32B includes lower ends 34A and34B respectively and upper ends 36A and 36B respectively. A toptransverse member 38 connects between upper ends 36A and 36B to completea rigid upside down U shaped upper portion 30.

As can be best seen by referring to FIGS. 3-8, lower ends 34A and 34B ofside members 32A and 32B are pivotably mounted to the upper end 18A and18B of bottom members 16A and 16B respectively. The joints between thelower ends of side members 32A and 32B and the upper ends of bottommembers 16A and 16B are adapted to allow upper portion 30 to pivotcounterclockwise as viewed in FIGS. 3-8 between the raised positionshown in FIGS. 1, 3, 4, 5 and 6 to the lowered position shown in FIG. 8.In the alternative, relative movement between upper portion 30 and lowerportion 12 as upper portion 30 moves between the raised position and alowered position could be accomplished by a translation such as with atelescoping structure or by a pivoting parallelogram structure or thelike. The pivoting structure shown and described in this example ismerely one way of accomplishing movement between a raised position and alowered position. The remaining elements of the raising and loweringmechanism which will be described in greater detail below, are, out ofnecessity, adapted to function with a pivoting structure.

As can be seen in FIGS. 3-8, in this example, lower portion 14 and upperportion 30 include a lock which is biased to secure upper portion 30 inthe raised position when upper portion 30 is in the raised position. Ascan be seen in FIGS. 4-8 by viewing only one side of roll bar assembly12, the lock for securing upper portion 30 in the raised position shownin FIG. 4 is a latch mechanism 40 which includes a latch member 41 whichis pivotably mounted to a bracket 20 to pivot about a shaft 41A which iscarried by bracket 20. Bracket 20 is fixed to upper end 18A of bottommember 16A. As can be best seen in FIG. 6, latch member 41 includes anotch 41B that is shaped to engage a rod 42. Rod 42 is generallyhorizontal and oriented transversely and is fixed to a bracket 35 thatis fixed to the lower end 34A of side member 32A of upper portion 30.Latch member 41 is biased by a spring 43 toward the latched positionshown in FIGS. 4 and 5. Thus, latch member 41 is biased by spring 43 tosecure upper portion 30 in the raised position. Latch member 41 furtherpresents a boss 41C. A cam 44 is rotatably mounted to a bracket 35 forrotation about an axis passing through the center of shaft 36 (shown inFIG. 4). Bracket 35 is fixed to the lower end 34A of side member 32A ofupper portion 30. Cam 44 engages boss 41C with two portions: a firstrecessed cam portion 44A and a second offset cam portion 44B. As adownward movement of cable 102 rotates cam 44 counterclockwise as viewedin FIGS. 3-8, boss 41C of latch member 41 is contacted by second offsetcam portion 44B of cam 44 which has a larger radius than first recessedcam portion 44A. This urges latch member 41 out against spring 43 anddisengages latch member 41 from rod 42. This unlatches upper portion 30from lower portion 14 and makes it possible for upper portion 30 to folddown relative to lower portion 14. The skilled reader should understandthat the same latch and cam mechanism is preferably identically repeatedon the opposite side of roll bar assembly 14 between upper end 18B ofbottom member 16B and the lower end 34B of side member 32B. The skilledreader should further consider that the latch mechanism described aboveis merely one way to provide a lock that is biased to lock upper portion30 in the raised position. A multitude of other mechanisms well known inthe art, may be selected for providing such a biased lock that can beselectively disengaged to allow upper portion 30 to move to a loweredposition. Just one example of an alternate locking mechanism mightinclude a spring biased pin which engages corresponding holes in lowerportion 14 and upper portion 30 which align when upper portion 30 is inthe raised position. The spring biased pin could be connected to theraising and lowering mechanism such that it is urged against its springbias to unlock upper portion 30 when an operator applies a force tolower upper portion 30.

Raising and lowering mechanism 50 includes an operator lever 100 and aspring assembly 60. Raising and lowering mechanism 50 functions incombination with an operator lever 100 to cause the lowering and raisingof upper portion 30.

We will first consider how raising and lowering mechanism 50 functionsto lower upper portion 30 from the raised position to the loweredposition. In this example operator lever 100, which may take the form ofa handle or a pedal, is connected by cable 102 to cam 44. In thisexample, cable 102 connects to a sliding bracket 22 shown in FIGS. 3-8.An upper cable portion 102A connects between sliding bracket 22 and apin 102P that is mounted to cam 44. As can be seen in FIG. 3, a shaft 64extends between cam 44 and a cam 144 that is mounted to the oppositeside of roll bar assembly 12. As can be seen in FIG. 4, cam 44 includestwo opposite, identical plates that are located on opposite sides ofupper end 18A of bottom member 16A. As can be seen in FIG. 3, the samearrangement exists for cam 144 on the opposite side for bottom member16B. Shaft 64 is fixed to both side plates of cam 44 as well as bothside plates of the cam 144 on the opposite side. Bracket 35 that isfixed to side member 32A presents ears on both sides of side member 32Awhich present co-axial bores for receiving shaft 64. A bracket 21 isfixed to the upper end 18A of side member 16A supports a bushing 36that, in turn, also receives shaft 64. Thus cams 44, 144, shaft 64 andupper portion 30 are all able to rotate about an axis A shown in FIG. 4.Axis A is fixed in relation to lower portion 14. As can be seen in FIG.4, bracket 35 mounted to side member 32A of upper portion 30 includes apin 35A which rides in a constant radius slot 44S. Also, a tensionspring 44S2 connects between cam 44 and pin 35A that biases cam 44clockwise toward pin 35A. Slot 44S, first recessed cam portion 44A andsecond offset cam portion 44B are arranged so that, as cable portion102A pulls on cam 44, cam 44 rotates counterclockwise as second offsetcam portion 44B rotates counterclockwise to encounter boss 41C of latchmember 41. As is shown in FIG. 5, and as described above, this causeslatch member 41 to release rod 42. Latch member 41 releases rod 42before the clockwise end of slot 44S encounters pin 35A. Once theclockwise end of slot 44S of cam 44 encounters pin 35A, (which is fixedto bracket 35 which is, in turn, fixed to upper portion 30) cam 44ceases its rotation relative to bracket 35. Since latch mechanism 40 isnow unlatched, cam 44, bracket 35 and upper portion 30 are now free torotate counterclockwise as seen in FIGS. 4-8 around the axis A (shown inFIG. 4) as cam 44 and bracket 35 are pulled by cable portion 102A. Upperportion 30 continues to rotates until it reaches the lowered positionshown in FIG. 8. if cable 102 and cable portion 102A continue totransmit sufficient force.

The operation described above occurs in reverse when the operatorreleases pressure from operator lever 100. As can be seen in FIG. 3, theopposite side of roll bar assembly 12 includes a spring assembly 60 thatbiases upper portion 30 toward the raised position. Accordingly, whenthe operator releases pressure from operator lever 100, upper portion 30rotates from the lowered position shown in FIG. 7 back to the raisedposition shown in FIGS. 3 and 4 with the exception that slot 44S and pin35A are in the relative positions shown in FIG. 4 during the returnstroke so that latch member 41 is in the position shown in FIG. 4 beforeupper portion 30 arrives in the position shown in FIG. 4. Accordingly,during the return stroke, pin 42A encounters a sloped upper surface oflatch member 41 to cause latch member 41 to turn out to receive pin 42A.Also because spring 44S2 biases cam 44 clockwise, boss 41C of latchassembly 40 remains in contact with first recessed cam portion 44Athereby maintaining latch assembly 40 in the latched position.

Operator lever 100 is shown in FIG. 2 as a foot pedal but can also be ahand lever or other such member for receiving force from an operator.Operator lever 100 is connected to a cable 102. Lever 100 is biased inthe position shown in FIG. 2 by tension which is applied by cable 102.Cable 102 routed to connect to sliding member 22 mounted to bracket 20of roll bar assembly 12 shown in FIG. 3. Cable 102 is in tension becausespring assembly 60 shown in FIG. 3 pushes cam 144 in a clockwisedirection as seen in FIG. 3 which in turn applies a torque to shaft 64which further pushes cam 44 in a clockwise direction to apply to anupper cable portion 102A which is connected to cable 102. When operatorlever 100 is up as shown in FIG. 2, cable 102 is not pulling down on cam44. When operator lever 100 is pressed forward by an operator, cable 102pulls on cam 44 which rotates counterclockwise as seen from theperspective of FIG. 3 which causes the release of latch mechanism 40 andthe lowering of upper portion 30 as described above.

The skilled reader will appreciate that, for example, an actuator may beinterposed between operator lever 100 and cam 44 so that the loweringand even the raising of upper portion 30 may be powered in response to aswitch which is activated by the rotation of lever 100. So, for example,in an embodiment having a powered actuator, lever 100 might close aswitch for activating a powered actuator and might also be biased towardthe position shown in FIG. 2, so that when the operator ceases applyinga force to lever 100, the switch would open and the actuator wouldreturn upper portion 30 to the raised position shown in FIGS. 1, 3 and4. As is well known in the art, power may be supplied to an actuator inany one of a number of forms including, but by no means limited to,hydraulic power, electric power and pneumatic power.

Second Embodiment

A second embodiment of the improved rollover protection apparatus,namely rollover protection apparatus 410, is shown in FIGS. 9-13. As canbe seen in FIG. 9, rollover protection apparatus 410 includes a lowerportion 420 and an upper portion 480. In this example, lower portion 420includes two upright supports 422 and 424 which are rigidly fixed tovehicle frame 402. Upper portion 480, in this example, is a generallyupside down U shaped member 482 which is pivotably mounted at its lowerends 484 and 486 to the upper ends of upright supports 422 and 424respectively. In this example, lower portion 420 also includes areleasable lock mechanism 490 which will be described in greater detailbelow. Releasable lock mechanism 490 is coupled to a lock releasingdevice, which in this example, includes a manually operable foot lever406 pivotably mounted to frame 402 and a lock actuation cable 406A. Footlever 406 may be replaced by any one of a number of actuation deviceswhich may even include electrically powered or hydraulically powereddevices which may be activated by a small manual input such as thepushing of a button or the toggling of a switch. When, in this example,foot lever 406 is pivoted by an operator from the position shown in FIG.9 to the position shown in FIG. 13, cable 406A is pulled. Cable 406A isconnected to releasable lock mechanism 490 so that, when cable 406A ispulled, releasable lock mechanism 490 initially moves from a lockedposition shown in FIG. 10 to a released position shown in FIG. 11. Whenreleasable lock mechanism 490 is in the released position, it ispossible for upper portion 480 to pivot from the raised position shownin FIG. 9 toward the lowered position shown in FIG. 13.

As can be seen in FIG. 9, upper portion 480 is pivotably mounted tolower portion 420 for rotation about axis AA. In FIGS. 9 and 13, axis AAis shown to be offset behind the centerlines of the members of upper andlower portions 480 and 420. As can be seen in FIG. 9, a bracket 484A isfixed to and extends back from the lower end 484 of upper member 482.Bracket 484A attaches to an upper portion cable which is used associatethe movement of upper portion 480 with releasable lock mechanism 490 aswill be described in greater detail below. A second set of oppositebrackets 484A and 484B extend from the opposite sides of the lowerportions of upper portion 480 and connect to a pair of upper portionreturn springs 482S1 and 482S2. Return springs 482S1 and 482S2 connectbetween brackets 484A and 484B and upright supports 422 and 424respectively of lower portion 420 and bias upper portion 480 toward theupright position shown in FIG. 9.

Releasable lock mechanism 490 can be better understood by referring toFIGS. 9-12. In this example, lock mechanism 490 includes a cam plate 492and a bell crank 496. As can be best seen in FIGS. 10 and 11, cam plate492 is pivotably mounted for rotation about axis A which is generallylongitudinal and bell crank 496 is pivotably mounted for rotation aboutaxis B which is also generally longitudinal. Cam plate 492 is springbiased in the counter-clockwise direction by spring 492A. As can be bestseen in FIGS. 10 and 11, bell crank 496 is connected at its oppositeends to two opposing rods 496A and 496B to which are pivotably jointedat their distal ends to two opposite latch pins 498A and 498B. Latchpins 498A and 498B are received by the co-axial bores of a clevisfittings 422A and 424A fixed to the upper ends of upright supports 422and 424 respectively and also by the aligned co-axial bores ofcorresponding lug fittings 484L and 486L fixed to lower ends 484 and 486respectively of upper portion 480. Thus, when these corresponding clevisand lug fittings associated with the upper and lower portions of theroll bar assembly receive latch pins 498A and 498B, upper portion 480 ofroll bar assembly 410 is locked in the upright position as shown in FIG.9. The skilled reader should observe by referring to FIGS. 9 and 13,that axis AA, which is the axis of rotation of upper portion 480 withrespect to lower portion 420, is offset from the center line of latchpins 498A and 498B, so that the hinge structure for the pivot jointbetween upper and lower portions 480 and 420 and latch pins 498A and498B secure upper portion 480 in the upright position as shown in FIG. 9when latch pins 498A and 498B are engaged as shown in FIG. 10. Theskilled reader can also observe that, in this example, lug fittings 484Land 486L have extending portion 484L2 and 486L2 which are generallysymmetrical and identical. Extending portion 484L2 may be best seen inFIG. 13A. As can be seen in FIG. 13A, extending portion 484L2 is shapedto block clevis 422C so that it is not possible for latch pin 498A toenter lug clevis 422C when upper portion 480 is moved away from theupright position shown in FIG. 9. The same arrangement is repeated onthe other side so that it is not possible for either latch pin 498A or498B to enter either clevis 422C or 424C respectively when upper portion480 is moved away from the upright position shown in FIG. 9.

As is noted above, in this example, cam plate 492 shown in FIG. 10 ispivotably mounted for rotation about axis A and is spring biased in thecounterclockwise direction. Bell crank 496 is pivotably mounted forrotation about axis B. As can be seen in FIGS. 10 and 11, bell crank 496presents a cam follower 496F which is normally received by a recess 492Rin the periphery of cam plate 492. As can also be seen in FIGS. 9 and10, the distal end of lock actuation cable 406A is connected to camplate 492. Still further, the proximate end of upper portion actuationcable 402 is also connected to cam plate 492 but by means of a pin 502Awhich is slidably received by a tangential slot 492TS defined near theperiphery of cam plate 492. The result of this arrangement is that whenlock actuation cable 406A pulls on cam plate 492, cam plate 492 rotatesclockwise through angle A1 from a first locked position shown in FIG. 10to a second unlocked position shown in FIG. 11. When this occurs, camfollower 496F of bell crank 496 is forced out of recess 492R whichforces the counter clockwise rotation of bell crank 496. All of this hasbeen arranged so that as cam plate 492 rotates by angle A between thefirst locked position to the second unlocked position, sufficientrotation of bell crank 496 occurs in order to withdraw latch pins 498Aand 498B sufficiently from the corresponding lugs of the lock structurecommon to upper portion 480 so that upper portion 480 can freely rotatefrom the raised position shown in FIG. 9 toward the lowered positionshown in FIG. 13.

Once the operator has depressed foot lever 406 sufficiently to withdrawlatch pins 498A and 498B from the respective fittings, and in particularlug fittings 484L1 and 486L1 as described above, thus unlocking upperportion 480 from lower portion 420, the operator may continue pressingfoot lever 406. When this occurs, lock actuation cable 406A continuespulling on cam plate 492. Recall that at this point, cam plate 492 is inthe unlocked position shown in FIG. 11 and the pin at the end of upperportion actuation cable 502 is at the extreme end of tangential slot492TS. Thus, now, cam plate 492 begins pulling on the proximate end ofupper portion actuation cable 502 as it continues to rotate clockwiseuntil cam plate 492 reaches a third upper portion fold down positionshown in FIG. 12. Note that in FIG. 12, cam plate 492 is rotated as faras possible in the clockwise direction, yet bell crank 496 has notchanged its position from FIG. 11. This is because the arc describingthe outer edge of cam plate 492 extending counterclockwise from recess492R is centered on axis A. Thus, cam follower 496F does not move evenas cam plate 492 rotates from the second unlocked position shown in FIG.11 to the third upper portion fold down position shown in FIG. 12. Asthe proximate end of upper portion actuation cable 502 is pulled to theposition shown in FIG. 12, the distal end of actuation cable 502 pullson bracket 484B shown in FIGS. 9 and 13. This causes upper portion 480to rotate down to the lowered position shown in FIG. 13.

Once upper portion 480 has cleared the overhead obstacle, and once theoperator has released pressure from foot lever 406, upper portion 480 isfree to return to the upright position shown in FIG. 9. Upper portionpivots back to the upright position at least in part because it isbiased to do so by upper portion return springs 482S1 and 482S2. Whenthis occurs, brackets 484A attached to the fitting at the lower ends ofmember 484 pulls on cable 502. Cable 502 then pulls on cam plate 492(shown in FIG. 12) to cause cam plate 492 to pivot in the counterclockwise direction from the position shown in FIG. 12 to the positionshown in FIG. 11. When cam plate 492 is in the position shown in FIG.11, upper portion 480 (shown to include members 484 and 486 in FIG. 11)is in the upright position (as is also shown in FIG. 9), but latch pins498A and 498B are still withdrawn from lugs 484L1 and 484L2 and at leastthe outboard portions of clevises 422C and 424C respectively. This isthe case because cam follower 496F is at the edge of recess 492R but hasnot been received by recess 492R. At this point cable 502 has no moretravel remaining to cause further counterclockwise rotation of cam plate492. At this point, spring 492A continues to pull cam plate 492clockwise as cam follower 496F rolls down into recess 492R. When thisoccurs, bell crank 496 rapidly rotates clockwise thereby allowing theoutwardly spring biased latch pins 498A and 498B to slide out toreengage lugs 484L1 and 484L2 and the outboard portions of clevises 422Cand 424C respectively. This causes upper portion 480 to be locked andsecured in the upright position shown in FIG. 9.

With the second embodiment apparatus 410 described above, it is possiblefor the operator to merely press lever 406 sufficiently to unlock upperportion 480 prior to encountering an overhead obstacle. With apparatus410 it is possible the obstacle itself could provide a force to pushupper portion 480 down while clearing the obstacle. Although this mightnot be a recommended way of using apparatus 410, and although it mightcause damage to either the obstacle or apparatus 410, less damage wouldlikely occur than would occur if an upright, fixed roll over protectionbar or hoop were to simply collide with an overhead obstacle. The abovedescribed apparatus 410, once unlocked as described above, is able torotate down toward the lowered position shown in FIG. 13 in response topressure from an obstacle. In such as case cable 502 would buckle whereit connects to bracket 484A (see FIG. 9). Extending portions 484L2 and486L2 of lug fitting 484L and 486L would block the retracted latch pins498B and 498A respectively from entering the space needed for lugs 484Land 486L until upper portion 480 was returned to the upright positionshown in FIG. 9.

Thus, such an apparatus would accommodate a mode where upper portion 480was merely unlocked to allow upper portion 480 to yield to an obstacleand wherein once the obstacle was cleared, upper portion 480 wouldreturn to the upright position and be secured and locked. Thus, theapparatus described above, provides a structure that can be folded downto avoid overhead obstacles, but which, as a default mode of operation,is locked in an upright position suitable for protecting an operatorduring a roll over, thus providing a more versatile and safer vehicle.

The structures described above merely provide example embodiments foraccomplishing the objectives of the invention. To accomplish theobjectives of the invention, it is essential that an upper portion of aroll bar assembly unlock in response to an operator input so that theupper portion can move to a lowered fold-down position. To accomplishthe objectives of the invention, it is also essential that the upperportion of the roll bar assembly be biased to return to the uprightraised position and to lock after the obstacle has been cleared.

It is to be understood that while certain forms of this invention havebeen illustrated and described, it is not limited thereto, except in sofar as such limitations are included in the following claims andallowable equivalents thereof.

1-4. (canceled)
 5. A rollover protection apparatus for a terrain workingvehicle, the rollover protection apparatus comprising: a lower portionand an upper portion movably coupled to the lower portion such that theupper portion is movable relative to the lower portion between a raisedposition and a lowered position; and a lock movable between a lockedposition and an unlocked position, the locked position securing theupper portion in the raised position; a lever coupled to the lock,wherein: upon an application of a force to the lever, the lock moves tothe unlocked position; and upon a cessation of the force to the lever,the lock moves to the locked position.
 6. The rollover protectionapparatus of claim 5, wherein the application of the force to the levermoves the upper portion toward the lowered position.
 7. The rolloverprotection apparatus of claim 5, wherein the upper portion is biasedtoward the raised position.
 8. The rollover protection apparatus ofclaim 7, wherein the cessation of the force to the lever moves the upperportion toward the raised position.
 9. The terrain working vehicle ofclaim 5, wherein the lever is one of a foot pedal and a hand lever. 10.The rollover protection apparatus of claim 5, wherein the levercomprises an actuator and a switch that is communicatively coupled tothe actuator.
 11. The rollover protection apparatus of claim 10, whereinthe switch has an open default state, wherein: the application of theforce closes the switch, and when the switch is closed the actuator iseffective to unlock the lock and move the upper portion toward thelowered position; and the cessation of the force opens the switch, andwhen the switch open state the actuator is effective to move the upperportion toward the raised position and lock the lock.
 12. The rolloverprotection apparatus of claim 11, wherein the actuator comprises apowered actuator and the switch comprises a button.
 13. The rolloverprotection apparatus of claim 11, wherein the application of the forcemaintains the switch in the closed state.
 14. The rollover protectionapparatus of claim 11, wherein the actuator retains the upper portion inthe lowered position when the switch is in the closed state and theupper portion reaches the lowered position.
 15. The rollover protectionapparatus of claim 11, wherein the actuator retains the upper portion inthe raised position when the switch is in the open state and the upperportion reaches the raised position.
 16. A rollover protection apparatusfor a terrain working vehicle, the rollover protection apparatuscomprising: a lower portion and an upper portion movably coupled to thelower portion such that the upper portion is movable relative to thelower portion between a raised position and a lowered position, whereinthe upper portion is biased toward the raised position; a releasablelatch pin movable between a latched position and an unlatched position,wherein a default position of the releasable latch pin is the latchedposition; a lever coupled to the releasable latch pin, wherein: upon anapplication of a force to the lever, the releasable latch pin moves tothe unlatched position; and upon a cessation of the force to the lever,the releasable latch pin moves to the latched position.
 17. The rolloverprotection apparatus of claim 16, wherein the application of the forcemoves the upper portion toward the lowered position and the cessation ofthe force moves the upper portion toward the raised position.
 18. Therollover protection apparatus of claim 17, further comprising a returnspring assembly that biases the upper portion toward the raisedposition.
 19. A rollover protection apparatus for a terrain workingvehicle, the rollover protection apparatus comprising: a lower portionand an upper portion movably coupled to the lower portion such that theupper portion is movable relative to the lower portion about an axis ofrotation between a raised position and a lowered position; and a lockmovable between a locked position and an unlocked position, the lockedposition securing the upper portion in the raised position; a levercoupled to the lock, wherein: upon an application of a force to thelever, the lock moves to the unlocked position; and upon a cessation ofthe force to the lever, the lock moves to the locked position.
 20. Therollover protection apparatus of claim 19, wherein the application ofthe force moves the upper portion toward the lowered position and thecessation of the force moves the upper portion toward the raisedposition.
 21. The rollover protection apparatus of claim 19, wherein theaxis of rotation is longitudinally offset from the lock.
 22. Therollover protection apparatus of claim 19, wherein the lever comprisesan actuator.
 23. The rollover protection apparatus of claim 19, whereinthe lock comprises a latch mechanism.
 24. The rollover protectionapparatus of claim 23, wherein the latch mechanism comprises a latchmember biased to the locked position.